Stereoscan Operators Log

While repairing, maintaining, or using the Stereoscan S200 SEM, please add notes here. Newest at top.

• After more thought, I've come to the conclusion that the column isn't actually missing a gasket on the specimen chamber mating surface. The column fits into a tapered bore inside the top of the chamber, and at the very tip of the column is a thick rubber fitting with a small hole for the beam to pass through. It's this very small air path that gets pumped down when the vacuum is operating, and the surface that makes the pressure seal is the rubber tip to the bottom of the taper, not the two flat disks where the column is bolted in. Plasma (talk) 21:05, 22 April 2014 (PDT)

• The replacement O-ring appears to fit on the side vent pipe of the SEM. With some help I was able to remove the column and do a cleaning of all the surfaces, save for the two detectors. It would appear we're missing a gasket for the column to chamber mounting interface, however. 4" ID, 4 3/8" OD, 1/8" thickness. I'll look to see what I can find.

Without that gasket it'd be a metal to metal vacuum fitting, and that doesn't seem right.

There's still some contamination on the bottom of the column I couldn't get off with just acetone. I'll try M.E.K. next time. Plasma (talk) 11:12, 22 April 2014 (PDT)

• Latest version of Xilinx ISE software does not support Spartan 3E board. Probably need 10.x version from http://www.xilinx.com/webpack/classics/wpclassic/ . Mirage335 (talk) 06:43, 12 April 2014 (PDT)

• Dan Barlow commented the following on our mailing list, April 4, 2014:

1. Ran the Edwards vane pump. Checked the oil. Looked up the specs and maintenance requirements.

-> I recommend not doing anything else to this pump unless there is an issue. It uses Ultragrade 19 oil, 0.6 Liter which is only about $17 plus shipping, but the current oil looks good.

1. Removed the Pfeiffer TPH190 turbo pump from the accordion flange and evaluated its mechanical condition.

http://wiki.hacdc.org/index.php/File:TurboConverted.avi It appears the pump was intended to hang from the plinth, but the glue holding the rubber donuts to the accordion flanges has failed. This is by far the easiest thing to fix, yay. I replaced the turbo but its cleats are only finger tight.

1. Identified and installed the vacuum system control cabling. Had to fix one bent pin. The final cable from the turbo controller to the turbo itself is NOT connected, so as to avoid accidental activation.
2. Identified starting backing vacuum for the Turbo, supposedly <5x10^-1 Torr to start, <5x10^-2 torr (warning possible unit conversion failure, anyway the safety interlock should handle this) back pressure for efficient operation to provide 10^-5 in the chamber. The thing moves 190 liters per SECOND and rotates around 30000 RPM. It has a magnetic bearing in the top high vacuum side and a oil lubricated ceramic bearing at the roughing end.
3. Identified alternate high vacuum options in case the turbo doesn't work. Looks like we could build an ion/titanium sublimation pump with our existing equipment and while not as fast it certainly works.

• To help keep a TCO log, I am noting that research on replacement electronics systems cost 5 hours. Mirage335 (talk) 17:14, 3 April 2014 (PDT)

• From Tim: the red vacuum gauge sticking out of the back of the chamber is a cold cathode vacuum gauge. They're pretty reliable, but it could fail to read vacuum, indicating it needs to be cleaned. Plasma (talk) 13:07, 2 April 2014 (PDT)

• The following steps need to be performed on the Edwards roughing pump:

• • Replace the oil
  • Inspect and clean the inlet-filter
  • Clean or replace the gas-ballast filters
  • Clean the motor fan-cover
  • Test the motor condition

Refer to pg. 38 of the user instruction manual

Plasma (talk) 23:02, 1 April 2014 (PDT)

• Use ~~~~ to automatically sign edits with username, date, and time. Mirage335 (talk) 08:21, 1 April 2014 (PDT)

• March 31st: Cleaned the plinth and took photographs of the vacuum components. Available here. -Dan K.

• Oil diffusionTurbo molecular pump was hanging due to the lip falling out of the rubber suspension. Could be cleaned and probably popped back in.

• Broken switch on roughing pump was bypassed internally. Plugging in the outlet should activate the pump. (This pump normally runs 24/7 when the machine is operational.)

• Compressed air needed to get more dust out

• March 30th: Moving complete! The SEM is now in the workshop

• March 29th: Awaiting pick-up and installation (March 29th and 30th).

• March 23rd: A space in the workshop has been cleared. Photo: http://i.imgur.com/BDNWL5z.jpg